ISSN:0193-2691    

DOI:10.1080/01932699908943853

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Vitamin E is widely used in pharmaceutical, food and cosmetic preparations.This paper discusses methods of preparing vitamin E emulsions by using sulfobetaine (SB) zwitterionic surfactants which have high electrolyte tolerance. The amount of vitamin E dissolved in water was analyzed by turbidity and UV absorption measurements. The emulsion droplet size was determined by laser light scattering. Microemulsions with small particle size and high resistance to oxidation in air can be obtained by solubilizing vitamin E in SB solutions at high concentrations (above %) The performance of a series of SB surfactants is compared in 1.5% solutions. A SB surfactant with a 12 carbon chain seems to be the most effective in dissolving vitamin E. The saturation value of vitamin E is increased about one order of magnitude by adding NaCl to the SB surfactant solutions. Emulsions formed in surfactant solutions containing NaCl (0 4-0.6 M) are stable at low surfactant concentrations such as 0.2-0.4 % The emulsion droplet sizes are below or around 200nm.

ISSN:0193-2691    

DOI:10.1080/01932699908943854

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

We investigated the effect of oil droplet size on the oxidation rate of DHA monodispersed emulsion with xanthan. Xanthan-free emulsions creamed rapidly but no creaming was observed in the emulsions containing xanthan over 8 weeks. While the peroxide value (POV) of the xanthan-free emulsion reached 10meq/ kg at 20 days, that of both emulsion systems containing xanthan changed little during the first 20 days. The POV for the emulsion with small droplet was higher than that for the emulsion with large droplet.

ISSN:0193-2691    

DOI:10.1080/01932699908943855

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The structure properties of isotropic solution are studied with the electrochemical methods for SDS/ n-C4H9OH/H20 system. The measurements of the conductivity show that the isotropic range in the phase diagram is composed of three areas with different structures: OAV structure connecting with water corner, bicontinuous structure in the middle area and W/ O structure connecting with n-C4H9OH corner. This result has been proved by the measurements of eletrochemical diffusion coefficient. The middle phase microemulsion shows bicontinuous structure. The solubilization fraction of n-C4H9OH in SDS micelle is about 0.98.

ISSN:0193-2691    

DOI:10.1080/01932699908943856

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The surfactant, sodium 3-dodecy] ether-2-hydroxypropyl-l-sulfonate(SDEHS) was synthesized. The association and standard free energy of formation of the complex between sodium 3-dodecyl etheT-2-hydroxypropyl-l-sulfonate(SDEHS) and polyvinyl-pyrrolidone(PVP) in an aqueous solution have been investigated using C NMR, ESR spectra, and surface tension measurements at the air/ water interface.13C NMR and ESR spectra all indicate that the basic structure of the complex is a micelle-like aggregate, the SDEHS molecules assembling on the methylidync(a) the methylene(α ) carbon in the backbone, and the methyleneβ carbon attached to the nitrogen of PVP molecules, and shield hydrocarbon groups on the surface of the micelle from contacting with water. The measurement results ofsurface tensions show that the amount of surfactant bound to the polymer are linear function of the polymer concentrations ( φ,WI% )i. e( c2-c1and the miceltization in the presence of PVP occurs at a lower concentration than the critical micelle concentration of SDEHS. The effectiveness of PVP in lowering the free energy of formation of the surfactant aggregates in aqueous solutions increases with the concentrations of PVP.

ISSN:0193-2691    

DOI:10.1080/01932699908943857

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The effects of vitamin C are determined in the oil-in-water(0/ W) and water-in-oil(W/ 0) microemulsion regions of CTAB/ pentanol/ p-xylene/ H20 system. The addition of Vc joins the O/ W and W/ O areas in the phase diagram and expands the bicontinous region by reducing the lamellar liquid crystal one. The results show that the “ coupling action” of Vc is in fact a structural transition from lamellar crystal to isotropic phase with W/ O, O/ W and bicontinous structure.

ISSN:0193-2691    

DOI:10.1080/01932699908943858

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Adsorption of Ethoxylated Nonyl Phenol (ENP) surfactant from its aqueous solution onto a commercial tire cutting from different sites. Outer Peristalitic (O.P.), Outer Smouth (O.S.), and Internal Tire (I.T.) is studied after different immersion times, 24, 48, 72, and 144 hrs at 30° C. The adsorption isotherms are determined by a surface tension method. A two stepped L-type isotherm is characteristic below the CMC of ENP; above this concentration the isotherm deviates from the L-type and the slope of the isotherm increases sharply. A Langmuir fit has been found below the CMC of ENP. From the maximum amounts adsorbed at pseudo-plateau (Tmaxof the tested samples it was found that the efficiency of adsorption onto the rubber surface decreases in the order, O.P. > O.S. > I.T.

ISSN:0193-2691    

DOI:10.1080/01932699908943859

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The phase behavior of Eucalyptus oil/ Tween 20/ Butanol/ Water and Eucalyptus oil/ Tween 20/ Cinnamic Alcohol/ Water systems have ben studied in detail. Both triangular and tetrahedral representations have been considered to understand the topological nature of the multicomponent mixtures. Shear viscosities of typical multiphasic compositions have been measured at different rates and temperatures. The samples have undergone shear thinning. The effect of temperature on the volumes of multiphasic compositions have been also investigated both increase and decrease of the extents of different phases have been witnessed. The enthalpy of dissolution of both water and oil in presence of amphiphile solutions in oil and water respectively have been determined calorimetrically. Considering the phase separation point to be the point of maximum solubility of microdroplets, the free energies and hence entropies ofsolution have been estimated. The above phy.sicochemical features have been also examined in presence of additives, viz, NaGI and urea.

ISSN:0193-2691    

DOI:10.1080/01932699908943860

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The solubility regions of the sunscreen 2-ethyIhexyl p-methoxycinnamate (E557) in the CTAB/ n-CsHnOH/ H2O system with and without the hydrotrope agent vitamin C (VC) are determined. E357 was only sohibilized in the bicontinuous microemulsion (BI), the W/ O microemulsion area and the lamellar liquid crystal region (LLC). The addition of VC in the system greatly enlarged the solubility amount of E557in the bicontinuous region, but reduced h in the lamellar liquid crystal area. Small angle X-ray diffraction measurement was used to determine the location of E557in the lamellar liquid crystal showing the suncreen molecule penetrating between the hydrocarbon chains in the liquid crystal structure.The UV absorption spectra of E557 in various media was measured, surprisingly showing a dependence on the colloidal structure.

ISSN:0193-2691    

DOI:10.1080/01932699908943861

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Some physico-chemical properties of aqueous racemic Ketorolac Tromethamine (KT) solutions were measured as a function of concentration (0-1.0 M). These included surface tension, osmolality, partition coefficients and electrical conductivity at different temperatures (10, IS, 20, 25, 30, 40 and 50° C). These measurements indicate that KT undergoes nonmicelar self-association in water. Comparison of thesolubilitiesof spironolactone and diazepam in aqueous KT with the corresponding solubilities in known aqueous hydrotropic agents (sodium benzoate and salicylate) nonmicellar chlorpheniramine maleate (BP grade of ⩽ 99 % purity) and miceilar chlorpromazine hydrochloride (BP grade of ⩽ 99 % purity) indicates KT to undergo nonmicellar association, with a capacity for solubilization intermediate between hydrotropic agents and miceilar solubilizers. The solubilities of normal alkanols (C4-C10) were also measured against aqueous KT concentration. Compared with their solubilities in miceilar surfactants (sodium dodecylsulfate and chlorpromazine hydrochloride) aqueous KT appears to be a less efficient solubilizer. Molecular mechanical modeling of intermolecular interactions between KT species in water indicate that trimeric species have lower energies compared with those of the same number of monomeric (or monomeric plus dimeric) entities.

ISSN:0193-2691    

DOI:10.1080/01932699908943862

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor